posted by Khaalid .
Phosphate standards used to generate the calibration curve are usually made by first preparing a stock solution of known concentration, then diluting it to the required concentration.
First prepare a stock solution that is 1.00 x 10-2 M in phosphate ion. How many g of Na3PO4 would you add to a 50 mL volumetric flask to to prepare this solution?
Second, what is this concentration in ppm of phosphate?
How many moles do you need to prepare the stock solution? moles = M x L = 0.01M x 0.050 L = ??
Since 0.01M in PO4^-3 is the same as 0.01M in Na3PO4, moles Na3PO4 will be the same as moles PO4^-3.
Then moles = grams/molar mass. Solve for grams Na3PO4.